Airways traffic control system



s. N. wlGHT ETAL AIRWAYS TRAFFIC CONTROL SYSTEM Jan. 18, 1949.

Filed Dec. 24, 1942 9 Sheets-Sheet 1 Snventors y 5. Fl' e ld MAZ /NWghTf cmdy O.

THEIR Gttorneg S. N. WlGHT ET AL AIRWAYS TRAFFIC CONTROL SYSTEM v Jan. 18, 1949.

9 Sheets-Sheet 2 FIGZB.

Filed Dec. 24, 1942 s Nw'isg ht andi o sff ld www THEIR G'ttorneg Jan. 1.8, 1949. s N wlGHT ETAL 2,459,399

AIRWAYS TRAFFIC CONTROL SYSTEM Filed Dec. 24, 1942 f 9 sheets-sheet 3 FIGQZ'C.

XC ReZaz'z/eangzllar mouemenfs equals E( m lm ,Der um of cz'sanee xc Distance Gear Patio A lii'.

.5. NWig ht and O. 5. Fie ld MMM Jan. 18, 1949. s. N. wlGHT ET A1. 2,459,399

AIRWAYS TRAFFIC CONTROL SYSTEM Filed Deo. 24, 1942 9 sheets-sheet 4 xm A51 P132 A152 ratio 11.024

85m SNWght and 0.5.Fl`eld E MMM Y THEIR (ttorncg Jan. 18, 1949.

s. N. wlGHT ET AL AIRWAYS` TRAFFIC CONTROL SYSTEM 9 Sheets-Sheet 5 Filed Dec. 24, 1942 Som HT Illim E VA I e @MYM TH En?. Ctforneg MMM-u H nooom Am HU L13 V@ mm m@ Jan 18, 1949. s. N. wlGHT ET AL 2,459,399

AIRWAYS TRAFFIC CONTROL SYSTEM Filed Deo, 24, 1942 9 Sheets-Sheet 6 Inwenfors Jan. 18, 1949. s. N. wlGHT ET AL 2,459,399

AIBWAYS TRAFFIC CONTROL SYSTEM Filed Deo. 24, 1942 9 Sheets-Sheet 7 Stati-ons A B First Calgulationc D 'E F Miles of Se eration o .w Arrival time it 50 mphrha 2.0 2100 oclo 3`o\ 62001?0 8100 2go 12100120 12200 Correction in each otretch speed increased to 100mph .Shaft XO `1\ \`2\\ ik \\2`\ \1 Add o 1 4 7 1o 1o Integration of corrections \`A\\ 1 made in rear shafts Y I 0- rr--l- -.\-4 --X Add Arrival time 100e-clock .5I00oclock400 o-clock 6-'00oclock200 Second Calculation Arrival time at 50 mphshaft Z 000, ZIOOoclock 6-00 6300 12200 w00 Correction in each etretchepoed y increased to 200 mphshaft X 0 -1-'0` x -1-0` -d -150 Add o ordo s:o\\ 6:50 ook 12:50 Integration of corrections ymade in rear shafts Y 0 0* l -lfO- d150 -6 Si Add Arrival time O OOoclock 1250 2:00 5500 350 Tgird Calculation Arrival 'time at 50 mph- `.Shaft-Z .starting time: 220 Z220 420 o-clock '20 10:20 14120 1G20 Correction in each stretch speed increased to 100mph-ahaft Xi Ox -1 -i? -1\ E d -1 Add @zo `5:20 o:2\\ e.2o\\ 1212EA 15120 Integration of corrections made in rear shaft. Y 0-5 O -1100 --53t00" 4.' -6.

Add=Arri`va| time 2720 S200-clock 520 620 8220 9.20

Fourth Calculation Arrival time at 50rnphshaft Z0 2-00oclock 0:00 8f00 12.00 14100 Correction in each .stretch .speed increaed to iOOmph- .Shaft X 0` 1` -2` -1 d 2\ -1 Add o\ 1\. 4 7 1o\ 1s Variable Factor corrections-time l condumedshafts V o.\ 10:30` +o:ao +1150` --1` -o-so Add o 1:50 4:ao\\ 7150 9 12:50 Integration of corrections made in rear shaftY olo --\--o:ao `2do L-zao--L-aao Add Arrival time 1:50 o-clock 4:00 5-50 650 T00 Fifth Calculation Infinite mph .starting time=0000 0300 oc|ock 000 0-00 0200 000 Correction in each .stretch speed decreased T0100 mph shaft' X+0200\ +100\ +220@ +1500- +2!00\ +i`00 Add ozoo 1:00 zoo 1:00 2:oo\ 1:00 Integration olfcorrection I Y made in rear .shaft Y 0I00-000 --\`--1.`00 --L52O0 ---`\4100- \-600 Add OO tooo-Clock 500 41'00- $0321 DeMogol) FIG 5 oni/Vigni and oorield TH E112 (Itlomeg Jan. '18, Av1949.. s. 1\1.'w1c-'.HT ETAL.v 2,459,399

IRWYS TRAFFIC C NTROL SYSTEM VFiled Deo. (24, 1942 v9 y'Sheets-Sheet 8 vSnventors Nwght and O. 5. Field TH EIR I. Cttorneg rlkllllll .IIlIIl Jan. 18, 1949. s. N. wlGHT ETAL 2,459,399

A Y IRWAYS TRAFFIC CONTROL SYSTEM I Filed Den..A 24, 1942 9 sheets-sheet 9 Fbze Enc/l /lvD/cn roze.

IF'. G 651962675 ,B-coman.

l mwrauem jfl/6:32 1 3 NUMBER, 0N lfm/667025 AEE V/SHBL! UNLV Nwighfmd o5 Frmd M y B G j 159 f2s w M'- w TH EH? (lttorneg Patented Jan. 18, 1949 UNITED STATES PATENT OFFICE AIRWAYS TRAFFIC CONTROL SYSTEM Sedgwick N. Wight and Oscar S. Field, Rochester, N. Y., assignors to General Railway Signal Company, Rochester, N. Y.

Application December 24, 1942, Serial No. 470,018

34 Claims. l

The present invention relates to airplane dispatching and more particularly to apparatus for displaying on a panel board authorized plane flights at various altitudes over a geographic route (route on the ground) and 'for displaying at each check point and station the arrival time for the plane.

It is essential that a dispatcher be properly informed as to arrival times of airplanes at various locations and altitudes to avoid the simultaneous arrival of a plurality of planes at the same station or check point and traveling at the same altitude to thereby avoid the possibility of a collision. In View of the high speeds at which airplanes fly it is not only necessary to calculate v the arrival times very quickly and accurately but it is also essential that they be displayed as quickly as possible. These various stations or check points are commonly terme fixes in the parlance of air navigators.

In view of the above and other important considerations, it is proposed in accordance with the present invention to construct a calculator for each geographic route to calculate the arrival times at a plurality of successive fixes or check points if the starting or base time at the starting station and the speed of the plane between each pair of adjacent check points or fixes is known. Since each of the distances between such adjacent check points or ixes remains fixed and is known, such distance factors are preferably built into the calculating machine itself.

It is further proposed to provide means for making variable factor corrections individual to each stretch between adjacent check points and to have these corrections integrated into arrival times for all subsequent check points on the route.

It is further proposed to employ arrival time indicators on a panel or ight progress board for the various altitudes at each fix or check point and provide apparatus for either manually displaying the calculated arrival times or semi-automatically setting arrival time indicators signifyparticular plane night or route in accordance wi the time calculated on. such calculator when a particular route and the direction of plane travel thereover is known.

Tt further proposed in accordance with the present invention to provide automatically operated recording to record on a record .sheet each complete indication that Was actually displayed on the panel or ight progress board.

Other objects, purposes and characteristic features of the invention will in part be pointed out hereinafter in the specification and will in part be obvious from the accompanying drawings in which:

Fig. 1 shows the control and ilight progress display board on which the apparatus of the invention is mounted;

Figs. 2A, 2B and 2C illustrate the units for the iirst three stations or fixes of an eastward route arrival time calculator;

Fig. 3 is an isometric exploded view of the apparatus and gearing for the unit for station B shown in Fig. 2B of the drawings;

Figs. 4A and 4B illustrate the circuits and associated apparatus for transferring the arrival times indicated on the calculator shown in Fig. 2 to the arrival time indicators shown in Fig. 1;

Fig. 5 shows tables to illustrate how the various shafts of Fig. 2 add the various positive and negative time increments to indicate arrival times at the various check points and stations;

Fig` 6 shows a modified indicating board on which the starting and arrival times are written in by hand;

Figs. 7, 8, 9 and 10 illustrate a modified form of starting and arrival time indicator operable from contacts of the calculator illustrated in Figs. 2 and 3; Figs. 8, 9 and 10 being sectional elevations taken on the dot-and-dash lines 8-8,19-9 and I IJ-Il), respectively, of Fig. 7 as viewed in the directions of the arrows;

Fig. 11 illustrates a recorder and a circuit structure for controlling the indicator shown in Figs. 7, 8, 9 and 10 by the calculator shown in Figs. 2 and 3 and for recording the indication displayed on this indicator; and

Fig. 12 indicates the relative time quantities associated with. the calibrations of the cruising speed dial EC shown in Fig. 2B.

Control and indicating desk- The control and indicating desk upon which the present invention is superimposed is shown in Fig. 1 of the drawings where a desk constituting an inclined plane DESK has mounted thereunder an east calculator for calculating arrival times for eastwardly moving airplanes and a west calculator for calculating the arrival time of westbound airplanes. A1- though the inter-connected gears of the calculators are mounted under the desk the control knobs and indicating wheels project through the desk and are visible above the desk. The eastbound. calculator is shown in the upper half of the desk whereas the Westbound calculator is shown in the lower half of this desk. This eastbound arrival time calculator is shown structurally and more speccally in Figs. 2 and 3 of the drawings whereas the westbound calculator has not been shown in detail but is of exactly the same construction as is the eastbound calculator except that its starting or base time setting dials are at the right-hand end and integra tion is made toward the left whereas the starting or base setting dials for the east calculator are at the left-hand end and integration is made toward the right. Each of these calculators, as will be more fully pointed out hereinafter, is constructed to provide gear ratios and gear relationships so as to take into consideration during its calculation of arrival time the distance between adjacent stations or check points. Although the eastbound calculator will be more fully described hereinafter it may be pointed out that it includes a cruising speed knob EC, variable time factor control knobs EVAB, EVBC and EVCD, and combined hour and minute control knob and indicators EHA, EMA; EI-IB, EMB; EHC, EMC; and EHD. The cruising speed knob is provided with a latch or lock ELC whereas the variable time factor knobs EVAB, EVBC and EVCD are provided with latches ELAB, ELBC and ELCD, respectively. The indicating and control knobs and latches for the west calculator shown on the lower half of the plane of the desk DESK have been designated by letter reference characters which are the same as those for the eastbound calculator except that the letter W has been substituted for the letter E in each reference character.

To the back and above the control desk is provided a flight progress board or panel board PL which illustrates panels signifying altitudes of 3000, 4000, 5000 and 6000 feet respectively over a geographic air route and shows three separate tiers, layers or shelves for signifying three different planes ying over the same altitude over the same geographic route portion, these tiers having been designated by the number of the altitude and an associated exponent 1, 2 or 3. as the case may be. The geographic air route illustrated in Fig.A 1 extends over fixes or check points A, B. C and D respectively and 'for each tier in each altitude there has been illustrated an indicator or number box IA for each nx or check point. Adjacent each one of these indications IA, IB, IC, etc.. there is provided a token receptacle THA, THB, THC, etc. respectively. As shown in Fig. 6 these indicators may constitute pieces of slate or frosted glass upon which the arrival times may be manually inscribed by chalk or by pencil for those systems in which the transfer from the arrival time calculator to the indieating panel is made by hand. In Fig, 1 of the drawings, however, the indicators IA constitute rotary drums of Fig.'4 or belts of Fig. 11 on which numerals are inscribed so that 'any timev from zero to twenty-four hours with the intervening minutes from 1 to 60 between successive hours may be indicated by the rotation of these drums. These drums are preferably electrically controlled as more specifically illustrated'in Figs. 4 and 7 of the drawings.

As shown in Fig. 1 of the drawings one particular iiight has been indicated on the panel board PL which for convenience is considered to be flight 9 as represented by tokens 9T. This particular airplane night set up on the panel board of Fig. 1 extends from altitude 3000 to 4000 between the fixes or check points YA and B and-extends from altitude 4000 to 5000 in its flight from xes or check points from B to C and ascends to altitude 6000 at rlx D. It should be noted that a particular flight is not necessarily displayed in the same tier of the various altitudes. For instance, ight 9 is displayed in the rst tier at locations A and B and in the second tier at locations C and D. This is done to allow for considerable flexibility and larger capacity.

As is more particularly pointed out hereinafter if .the starting or base time at fix A is set on the hour and minute knobs EHA and EMA with the cruising speed knob EC set at the proper cruising speed, the other hour and minute knobs EHB-EMB and EHC-EMC, etc., will all be turned to assume positions to indicate the arrival times at these more remote -fixes for a plane fly-- ing at the prescribed cruising speed. As illustrated on the panel board PL of Fig. l the starting time at stack A is 2:20 and if this starting time is 2:20 and the cruising speed is 100 M. P. H. the arrival times for stations B and C are 3:20 and 5:20 respectively on the assumption that the distance between stations A and B is 100 miles and the distance between stations B and C is 200 miles. The manner in which the shafts Z, X and Y calculate this arrival time is indicated by a tabulated analysis in Fig. 5 ithird calculation) of the drawings.

Arrival time calculator.--Referring to Figs. 2A. 2B and 2C of the drawings, which when laid side by side in that order constitute a three sta tion or iix calculator, the cruising speed knob EC has been shown in the upper left-hand corner of Fig. 2B in substantially the sanie 'way as it has been illustrated in the upper left-hand corner of the desk DESK of Fig. l. This cruising speed knob EC is normally held in its last operated position by a latch ELC whereas the variable factor control knobs EVAB, EVBC and EVCD are provided with similar holding latches ELAB, ELBC and ELCD. .A similar latch or lock is also provided for each of these knobs of the westbound calculator shown in the lower portion of the desk DESK of Fig. 1 which are designated by the same letter reference characters except that the letter E has been replaced by the letter W. This cruising speed knob EC is secured to the shaft X, which shaft extends throughout the entire length ci the east calculator as shown in part in Figs. 2A, 2B and 2C of the drawings. This shaft X therefore moves a given angular distance for a corresponding change in the anu gular position of the cruising speed knob EC, and a particular angular movement of the shaft X represents a unit of time per unit of distance, as will be discussed more in detail with reference to Fig. l2. This function of the shaft X has been indicated by a suitable legend applied to Fig. 2C.

Near the lower part of Fig. 2 or" the drawings has been illustrated a shaft Z upon which the Various hour indicating wheels H and minute indicating wheels M are pivotally mounted, this shaft also extends the entire length of the calculating machine and has secured thereto, as by a cross-pin, a sun-gear S at each or" the various locations. These sun-gears have been designated SAB, SBS and SC3 for the three l-ocations or fixes A, B and C illustrated in Fig. 2. This shaft Z acts through the sunagears just mentioned so that the setting of a starting or base time at the iix A will cause the proper positioning of the time dials at each of the successive xes; and similarly, if the time dials at :dx B for example are set in accordance with a base time, then the time dials at the nx C and remaining fixes of the route (not shown) are properly set in accordance with such base time.

It should be understood that although the calculating machine for eastbound traic has only been illustrated as of a length to take care of three stations that like units as those illustrated in Fig. 2B and Fig. 2C may be added to the right-hand end of the drawings of Figs. 2A, 2B and 2C to any extent within reasonable limits, and that in each case the gears will be exactly the same except for the gear ratios for the gears between shafts X and Y. The gear ratio in each case is selected in accordance with the distance between the pair of fixes with which it is associated. Between the shafts X and Z in Figs. 2B and 2C of the drawings have been illustrated the shafts Y, that is, a sectionalized shaft which consists of sections Y0, YI, Y2, Y3 and YI. The sections Y0 and Y2 are connected together by two planetary differential or epicyclic gearings including the shaft YI, and similarly the shaft sections Y2 and Y4 are connected together by t-wo identical differential planetary gearings including the shaft Y3.

Each of the epicyclic gearings connecting the adjoining sections of the time transfer shaft Y for a particular x interval between two adjoining xes permits the insertion of time both from the shaft X and the Variable time factor shaft V associated with that nx interval.

In order to get a more clear understanding of the gearing mechanism shown in each of Figs. 2B and 2C, and shown in part in Fig. 2A, it is beiieved desirable to make reference to Fig. 3 wherein the gearing of Fig. 2B has been shown in an exploded isometric view.

Referring to Fig. 3 of the drawings the shaft Z is pinned or otherwise fastened to the sun-gear SB3 as well as the sun-gears SA3 and SC3 (see Figs. 2A and 2C) and other more remote sungears. On this shaft Z at station B and adjacent the sun-gear SB3 is pivotally supported a gear ZB3 which meshes with the intermediate gear B25 which intermediategear in turn meshes with the gear YB3 pinned or otherwise secured to shaft Y2. The gear ZB3 is provided with studs or bearing pins 21 and 28 on which are pivotally supported planet gears PB3. These planet gears are in practice of substantially half the diameter o1' that of the sun-gear SB3 about which they rotate in meshed engagement. Just to the left of this sun-gear SB3 and pivotally mounted on the shaft Z are mounted two combined indicating and operating wheels or knobs, one of which, namely, the hour wheel, is designated EHB and has hour numerals from 1 to 24 ingraved thereon and spaced equally, whereas the other, or minute wheel, EMB has engraved thereon minute marks from l to 60 of which each fth mark is identified by its minute numeral. These minute numerals are in the order 5,. 10, 15, etc. As just pointed out this hour and minute wheel is each pivotally secured on the shaft Z and these hour and minute wheels will each be operated by the planet gears PB3 in a manner as will presently be pointed out. To the minute wheel EMB is xedly secured, as by studs 29 and 30, an annular gear AB3 which has an internal pitch diameter of substantially twice that of the pitch diameter of the sun-gear S183 and is provided with annular teeth engaging the teeth of the two planet gears P133, which planet gears in turn have their teeth also engage the teeth, of the sun-gears SB3. Since the sungear SBS is of substantially half the diameter as that of the annular gear AB3 the rotation of the shaft Z to an extent of 180 degrees, it being assumed that the gear ZB3 is held stationary, will cause the annular gear AB3 to rotate through an angle of substantially This relationship between the pitch diameter of these gears, although not absolutely necessary, is desirable and this relationship should be kept in mind in the study of this disclosure. Conversely, if the gear ZB3 is held at rest, as it normally will be through the medium of the various latches or locks L (see latches ELC, ELAB, ELBC, etc., of Fig. l), rotation of the minute wheel EMB through an arc of 90 will cause rotation of the shaft Z through an arc of The hour wheel EHB is similarly xedly connected to a gea!` ZB4 by studs 4I and 42.

'I'he annular gear AB3 is not only provided with teeth in its annular race but is also provided with gear teeth on its perimeter which latter gear teeth together with other gears maintain the proper relationship between the hour wheel EHB and the minute wheel EMB. That is the external teeth of annular gear AB3 mesh with the gear 42 connected to the pinion 33 by a shaft 34, which pinion 33 in turn meshes with the gear 35 connected to pinion 36 by a shaft 3l, which pinion 36 in turn meshes with a gear 38 connected to pinion 39 by a shaft 40, which pinion 39 meshes with a gear ZB4 directly fastened to the hour wheel or hour drum EHB as by studs 4I and 42. This train of gears 32, 33, 35, 35, 38 and 39 aiords a gear reduction oi 24 to l. In other words, rotation of the minute wheel EMB through one cornplete revolution causes one twenty-fourth of a complete rotation of the hour wheel EHB. In other words, the rotation of the minute wheel EMB through one complete revolution moves the hour wheel from one hour number to its next adjacent hour number. It should be understood that this gea;` reduction may, if desired., be of the intermittent type whereby the entire movement of the hour wheel from one number to the next higher one takes place during the movement of the minute wheel from the 55 to the 60 position..

From the foregoing it should now be understood that, if the gear ZB3 is held stationary, as it normally isy the rotation of the minute wheel EMB through one complete revolution will cause the hour wheel EHB to rotate in the same direction through of one revolution and will cause the shaft Z to rotate through two complete revolutions. Also, that if the next gear ZGB is held stationary such two complete revolutions of shaft Z will cause the minute wheel EMC to make a complete revolution in the same direction. The gear ZB4 which is directly connected to the hour wheel EHB directly drives a gear EHBl of the same diameter as the gear ZB4, and, and this gear EHB1 is directly .fastened to two Contact brushes EHTB and EHUB through the medium of shaft 44. These contact brushes EHTB and EHUB are more clearly shown in Fig. 4B of the drawing (see contact arms EHTA and EHUA) In a similar manner the annular gear AB3 drives a gear EMBv1 of the same diameter the' exterior diameter of the annular gear AB3 and this gear EMBl through the medium of shaft 45 drives a gear 5i having secured thereto a contact brush EMTB, also more fully shown for station A in Fig. 4B of the drawings where this contact arm is designated EMTA. This gear 5l directly meshes with a pinion 52 which has a pitch dia-meter substantially 1/6 of the pitch diameter of gear 5l so that the pinion 52 makes six revolutions for each revolution oi the gear 5 i. This gear 52 through the medium of the shaft 46 drives the contact brush EMUB, which brush for station A 7 is more clearly shown in Fig. 4B of the drawings and is there designated EMUA.

The gears associated with the shafts Y0, YI, Y2, etc. (see Fig. 3) may for convenience be called the integration gears in that they accumulate, by the rotation of gear YBI meshing with gear B26, the sum or difference of the rotation of the cruising speed knob EC and the variable time factor knob VAB. As shown in Fig. 3 of the drawings the shaft YQ is firmly locked against rotation by a pin 4381 held in the fixed. block 48 as a result of which the annular gear ABl is at all times held stationary, this annular gear AB! being secured to the shaft Y@ through the medium of a yoke 49. This section Y6 is the only portion of the entire shafts Y that is bolted against rotation. These shafts such as Y2, Yll, etc. may be properly termed time transfer shafts, since the time added or subtracted by the movement of shaft X or shaft V for each fix interval is transferred from the accumulator gearing associated with that fix interval to the accumulator gearing associated with the next fix interval. In this way, the iiying time for each successive fix interval is added to the flying time of all other iiX intervals lin the route. For example, the iiying time represented by the position of the gear YB! is transferred to the accumulator gearing associated with the X interval between fixes B and C and is added to the flying time represented by the position of the gear YC! with the sum appearing on gear AC2. This operation will presently be explained in greater detail.

On the shaft Y! is pivotally supported a gear YB! which supports the pivot pins 50 for supporting the planetary pinions PBI, so as to hold these planet pinions PBl securely in meshed relation with the teeth of the gear ABI. These planet pinions PBI are also held in meshed engagement with the teeth of the sun-gear SBI. The planet pinio-ns PBl are preferably of substantially half the diameter as that of the sun-gear SBI and the sun-gear is preferably half the diameter of the annular gear ABI. t is thus seen that if the gear YBl is rotated through a half revolution that the shaft Y! will be rotated through one and onehalf revolutions. Just to the right of the planetary differential reduction gearing just described and including gears YBI, SBI, PBI and ABI is provided a similar planetary diiferential reduction gearing including the gears YBZ, ABEL SBZ and PBZ except that this latter planetary differential reduction gearing is turned the opposite way end for end from that of the one just described. This is done so that rotation of the shaft YQ, if it were possible to rotate this shaft, with the cruising speed knob EC and the variable time factor control knob VAB held stationary the shaft Y2 will rotate to the same extent that the shaft Y is rotated. This is unimportant for the apparatus at station B but is of importance for like apparatus located at station C shown in Fig. 2C of the drawings and for other more remote stations.

It is now apparent that the three planetary gear systems including gears ABI, SBI, PB! and YBI; ABZ, SBZ, PBE and YBZ; and ABS, SBS, PB3 and ZBS-l respectively all have the same gear ratios and for this reason it is believed helpful to submit the following gear ratio relationship of each of the three systems: If the planet pivot supporting gear is held stationary the angular speed ratio of annular gear to the sun-gear is 1 to 2; if the annular gear is held stationary the angular speed ratio of the planet pivot support--4 8-1 ing gear to sun-gear is l to v3; and if `the sungear is held stationary the angular speed ratio of planet pivot supporting gear to annular gear is 2 to 3. Obviously, if the direction of the drive in each case is reversed the angular speed ratio will be the reciprocal of that given.

If we now assume that the shaft Z is held stationary and the gear YB! is rotated by the cruis ing knob EC it will be seen that this rotation of the gear YBI causes'the planet gears PBI to re volve within the annular gear ABI to cause rotation of the sun-gear SBI at thrice the extent of the rotation of the gear YBI. This thrice extentv of rotation of sun-gear SB! is reflected in similar rotation of the sun-gear SB2 which, if it is assumed that the variable factor knob VAB is held in locked position, will cause the shaft Y2 to rotate to half the extent of rotation of the sungear SBZ, so that the shaft Y2 rotates to an extent equal to one and one-half times that which the original gear YBI was rotated. If on the other hand the variable factor knob VAB is turned to rotate the gear YBZ to a predetermined extent, under conditions with the cruising knob EC held in locked position, this rotation of the gear YBZ will cause the planet gears FB2 to perambulate about the stationary sun-gear SBZ to in turn cause the shaft Y2 to rotate three-halves the extent of rotation of the gear YBZ. From the foregoing consideration it is apparent that rotation of the cruising speed knob EC or the variable time factor knob VAB or both will cause these two rotations to be accumulated into a sum of two or a difference of two rotations of the gear YB3 depending on Whether the gears YBI and YBZ were rotated in the same or different directions. It is also readily seen that if the shaft Z is held stationary the exnt of rotation of the shaft Y2 will be reflected in similar rotation of the minute wheel EMB and in turn a corresponding but reduced rotation of the hour wheel EHB.

Referring now to Figs. 2A, 2B and 2C, arranged side by' side, it will be observed that if the shaft Z is assumed to be held stationary, as for instance by holding it manually, the rotation of the cruising speed knob EC will cause rotation of the gear YBI to an extent depending on the gear ratio imposed between the gear XB and YB! by gears XB! and XE2, It may be pointed out here that this gear ratio imposed by gears XB! and )Q32 is dependent upon the distance between stations or fixes A and B whereas the gear ratio imposed by the gears XC! and XCZ (see Fig. 2C) is dependent upon the distance between stations B and C.

Referring to Figs. 2 and 3 the gear XB! has a diameter three-fourths the diameter of gear X132 so as to impose an angular speed ratio from gear XBI to gear XBZ of 3 to 4. As already pointed out the planet gears are half the diameter of the sun-gears and the sun-gears are half the diameter of the annular gears. Therefore, if the cruising speed knob EC is turned a one-half revolution, and bearing in mind that gears XB and YB! are the same in diameter, the gear YBI is turned two-thirds of one revolution, which turns the shaft YI two revolutions (the annulus ABI being bolted stationary), which turns shaft Y2 one revolution, which turns gear ZBS two-thirds of one revolution (gear YB3 having a diameter two-thirds of -thato'f gear ZB3) which results in the turning of minute wheel EMB one revolution.

In otherv words, 1/2 4/3 3 `12 2A 3/2=|1. This ratio is as it should be in that if the cruising speed is changed-by rotating cruising knob from the 50 11 from station A to station B is carried over into the arrival time indication given for station C.

Variable factor correction-Even though the air speed (speed in the air) of a level flying plane may be definitely known this does not mean that this is the ground speed (speed over the ground) in that the medium supporting the plane (air) maybe moving in any one or numerous directions. If the plane is travelling against the wind the ground `speed will be the diierence between the air speed and the velocity of the wind. If it is travelling with the wind the ground speed will be the sum of these speeds. If the wind is at right angles to the direction of night the air mile distance will be longer because the plane must fly the diagonal of a rectangle constructed in the moving air from the two speeds and therefore the plane will be delayed. Also if a plane makes an altitude climb it will be somewhat delayed whereas if it makes a descent its ground speed will be higher. 'I'he dispatcher and his assistants will by making rough calculations of the known factors, such as, direction and velocity of the wind, the make of the plane, the pilot and the flight whether ascending, descending or flying horizontal, conclude whether the variable factor correction shall be plus minutes or minus minutes and of what value. In order to inject this variable factor correction into the arrival time indications the variable factor knobs, one for each stretch, such as VAB, VBC, etc., have been provided. Referring to Fig. 3 if the variable factors sum up to save time the knob VAB will be turned in the minus direction to the extent of the time expected to be saved in the stretch from A to B and if it is a loss of time it will be turned in the plus direction.

Let us assume that five minutes will be saved in moving from station A to station B. The dispatcher will move the knob VAB to the minute position by turning the knob 30 degrees from its zero position. Rotation of the knob VAB through T12- of a revolution, in the direction of the arrow shown in Fig. 3, causes gear VAB1 to be turned to the same extent and in turn causes the gear YB2 to be turned times or 1/ia of a revolution toward the right, which turns shaft Y2 1/18 times 3/2 or 1% revolution toward the right (sun-gear SBZ being assumed to be stationary) which turns gear ZB3 l-l times %=2/ss or 1/is revolution toward the right which turns minute wheel EMB 1/ia times 3/2=3/3s or -g revolution toward the right namely from the 60 minute position to the 55 minute position. Had the variable factor reduced the plane speed more time would have been required and the variable time factor knob VAB would have been turned in the plus or counter-clockwise direction as viewed from the left. Not only was this ve minute turning of knob VAB effective in turning the minute wheel EMB backwards to the extent of 5 minutes but it was also effective, through the medium of shaft Y2 and the gears for station C, to turn the minute wheel EMC backwards Tlf of a revolution for reasons already described. As is apparent from Fig. 2B of the drawings the scale on the cruising speed knob EC is reciprocal in nature in the sense that the speed graduations are unequally spaced so as to turn the shaft a varying number of degrees for each different increment of speed. Obviously if a uniform speed scale on the cruising speed knob EC is desired a variable ratio reduction cam may be inserted between the cruising knob and the shaft X.

Operation of arrival time calcuZator.-Let us n'ow referto Figs'. 2 and 3 for illustrations of the calculator and to Fig. 5 calculations rst to fifth, inclusive, illustrating iive different calculations performedby the calculator. Referring to Fig. 5 it will be observed that at the extreme left of this figure an explanation is made for the various items in each of the tables given. In the first calculation of Fig. 5, line 1 designates the stations A to F inclusive. Line 2 designates the miles of separation between stations which for convenience are alternately and 200 miles. Line 3 shows the time of plane arrival for a speed of 50 M. P. H. as calculated through the medium of shaft Z and the planetary or epicyclic gearing mounted on this shaft Z. The next line shows the correction that is made, by turning the cruising shaft X from the 50 M. P. H. to the 100 M. P. H. position, insofar as the time saved in the next preceding stretch is concerned, the correction being made by shaft X. It should be understood that the cruising speed is read at the pointer 69 (Figs. 2B and 3). The sixth line shows the correction that is made by various sections of shaft Y and its associated gearing which integrates and injects into each arrival time indication the correction made at all preceding stations. In other words, if time is saved between stations A and B it not only results in a lower arrival time reading at station B but also results in a lower arrival time indication at each of the subsequent stations. By adding the correction made by shaft Y to the indications set up by shafts Z and X in combination the ultimate time of arrival indications are indicated in the last line of the Fig. 5, irst calculation.

'The various dotted lines and arrows shown in Fig. 5 of the drawings indicate the factors which are used in deriving the numerals added to the former time arrival indication. For instance, the -1 (minus one) shown in the second line of time numeralssecond column of Fig. 5, rst calculation, indicates that one hour is saved in a 100 mile stretch by increasing the speed of the plane from 50 M. P. H. to 100 M. P. H., as is also true of the -2 indicated for station C, the distance from stationv B to station C being 200 miles. Referring now to the numeral -3 in the fourth line of time numerals fourth column, this value is derived from the 2 hours gained by the plane in increasing its speed from 50 to 100 M. P. H. in travelling from station B to station C to which is added the -1 hour time gained by increasing the speed from 50 to 100 M. P. H. in travelling from station A to station B. This three hour gain is however not the only gain in arrival time for station D because another hour time is saved by the plane increasing its speed from 50 miles to 100 M. P. H. over the stretch from station C to station D as indicated by the -1 in the second line of time numerals column four. By subtracting these gains of four hours from the originally calculated time of 8 oclock will result in an indication indicating that the plane will arrive at station D at ll oclock. This is as it should be because irrespective of the distance between locations if the speed is doubled the time consumed should be halved.

The table showing the second calculation is identical to the table showing the first calculation except that. the cruising speed of the plane has been increased from 50 M. P. H. to 200 M. P. H. It will be observed that since the starting time is zero in both cases the arrival times indicated in the second calculation are in each instance half misdaan i3 as late as are the arrival times indicated in the first calculation.

Referring now to the third calculation 1t will be observed that the starting time at station A is not zero (24 oclock) as is the case in the first calculation but instead is 2:20. It should also be noted that in this third tabulation the speed of the plane is presumed to have been increased from 50 M. P. H. to 100 M. P. H. the same as in the first calculation and that all the arrival times indicated in the third calculation are two hours and twenty minutes later than those indicated for lthe first calculation.

Referring` now to the fourth calculation in Fig. 5 of the drawings it will be observed that the calculations here given also assume, like in the first calculation that the cruising speed of the plane has been increased from 50 M. P. H. to 100 M. P. H. and that the starting time for station A is zero in both cases. It should however be observed that in the fourth tabulation various factor corrections have been applied to each of the stretches from station A and station F, inclusive. The time lost from stations A to B, B to C and C to D, are assumed to be minutes in each instance, whereas the time gained in flying from station D to station E is assumed to be one hour and the time gained in iiying from station E to station F is assumed to be 30 minutes. This table constituting the fourth calculation analytically shows how Ithese various correcting factors have been applied not only to the arrival time indication of the immediate station for the stretch but such correction is also made to the arrival times of all subsequent stations toward the right. It will be observed that the time lost in travelling the first three stretches has been regained in travelling lthe last two stretches and for this reason the arrival time at station F in the fourth tabulation should be the same as the arrival at station F in the irst tabulation, and it will be observed that this is the case in these two tabulated analyses.

Thus far it has been assumed that the cruising speed knob EC shown in Figs. 2A and 3 normally assumes the M. P. H. position and that it is advanced to a higher speed when a calculation is to be made. This is not necessarily true because if the cruising knob EC should be turned one full turn toward the right from the position -1 shown in Fig. 2B, it would assume what might be called the infinite M. P. H. speed position. In practicing the invention, a stop is however preferably provided so that the cruising speed knob cannot be moved fully lto the so-called lnfinite speed position. If this cruising knob EC is assumed to be moved one full turn to the right (Fig. 2B) and the hour and minute wheels for station A are moved to their zero position (24 oclock position) then each of the indicators for stations B and C, as well as all subsequent indicators in the series, will assume their zero positions (see fth calculation of Fig. 5), and if the hour and minute dials for station A are moved to any other indicating position the corresponding dials at subsequent stations will all indicate the same position. lThis is true because these various hour and minute dials or wheels are directly connected through a continuous shaft Z extending through all indicatingmechanlsms. If now the indicating dials EHA and EMA for station A are held in their zero position and the cruising knob EC is turned from the infinite position toward the left to the particular cruising speed which a plane is presumed to ily each of 14 the indicating dials for the stations B, C, etc. will indicate the proper arri-.val time.

In tabulation five of Fig. of the drawings has been indicated a tabulated analysis under the conditions of zero starting time with the cruising knob rst assuming the infinite M. P. H. position, an absurdity, which is later corrected by moving this cruising speed knob EC to the M. P. H. position. No further discussion of this Fig. 5 fifth calculation is believed necessary, except to direct attention to the fact that the ultimate arrival times of the first and nith calculation of Fig. 5 are the same as they should be.

It is of course understood that if the cruising knob is moved after the starting time has been set for station A that the hour and minute wheels for station A must be held while the cruising knob EC is moved to its new position or else be corrected after the cruising knob is moved because turning of the cruising knob may change the starting time setting. In using the calculator illustrated in Figs. 2 and 3 it is assumed that the cruising knob and the various variable factor knobs aie first moved to the proper position after which the starting time for station A is set by manually turning the hour and minute wheels for station A. It should be understood that if it is found that the airplane has gained or lost time in travelling from station A to station B, that the minute and hour dials for station B may then be moved to the proper new starting time for station B as a result of which the newly corrected arrival times for all subsequent stations C, etc., will be indicated. As pointed out more fully hereinafter the new arrival time settings may be transferred to the indicators on the panel board after each correction by merely depressing the proper token.

As already mentioned the indicating scale on the cruising knob is reciprocal in nature. This is true because the time saved, namely, the difference between two successive time readings, each time the speed is doubled is half as much as the time saved during the preceding doubling of the speed. In other words, if we assume speeds of 50, 100, 200 and 4G() M. l?. H. respectively it requires 2, 1, 1/2 and 1/4 hours respectively for a plane 4to ily over a hundred mile stretch and the difference vbetween these times are i, 1/2 and 1/4 respectively. Since doubling of the speed only saves half of the time required at the preceding speed it is readily seen that a scale which approaches infinity as a limit is involved.

Transfer mechanism-fis already pointed out the hour and minute wheels EHB and EMB of the east-bound calculator for station B (see Fig. 3) have associated therewith rotary contact arms EHTB, EHUB, Ell/LTB .and EMUB. Similar rotary contact arms EHTA, EHUA, EMTA and EMUA are provided for the eastbound calculator for station A and these latter arms have been shown in Fig. 4B of the drawings. In these reference characters the letters E and W signify east and west, respectively; the letters H and M signify hour and minutej respectively; and the letters T and U signify tens and units respectively. Also the letters A and B denote the particular station with which the apparatus is associated.

These contact arms electrically manifest the positions assumed or indications given by these hour and minute wheels EHA and EMA (Figs. l and 2A). These contact arms EHTB, etc. are so keyed or otherwise secured, to the hour and minute wheels that if a particular set of digit numcasacca;

bers are read on these hour and minute wheels EHA and EMA correspondingly numbered wires will be energized. For instance if these Wheels EHA and EMA of Fig. 2A indicate 02 and 20 respectively, as assumed for the calculation given in the iifth table of Fig. of the drawings, the wires D' and 2 are energized by associated contact arms EI-ITA and EHUA, respectively, and the wires 2 and [l are energized by contact arms EMTA and EMUA, respectively. Similar contact arms WHTA, WI-IUA, WMTA and WMUA are provided for theunit A of the westbound calculator shown in Fig. l. These latter contact arms are shown in lower part of Fig. 4B of the drawings.

Referring now to Figs. 4A and 4B which when laid above each other show the apparatus and associated wiring for transferring the readings on one or the other of the two calculators (eastbound and westbound) shown in Fig. l to the indicators IA, etc., also shown in Fig. 1 by rotating each of these drums 53 of these indicators to the position where the proper numeral only is visible. These indicator drums 53 are hollow and are translucent with the numbers painted, or otherwise applied, to the inside of the drum so that the number is not visible from the outside unless the interior of the drum is illuminated. The lamps 56, 5l, 58 and 59 (see Fig. 4A) have been provided to illuminate the four drums 53 of in dicator IA for tier 30001 at station A (see Figs. l and 4A) Although in practice the mechanisms for operating these four drums is mounted back of the indicating drums this indicator has for convenience been shown in exploded form in Fig. 4A of the drawings with the operating mechanism for the drums in each case shown to the right thereof.

Each of the four drums 53 of these indicators IA, etc. is pivoted about a vertical axis and is provided with a spur gear 69 at the bottom end of its vertical shaft. This spur gear 60 is in meshed relation with a gear 6l constituting one clutch member of a clutch, the other clutch member of this clutch being splined to the clutch shaft 62 so that upon energization of the coil 63 of this electro-magnetic clutch the gear 6l will rotate with the shaft 52 but upon deenergization of this coil the shaft 62 and gear 6l will be operatively disconnected from each other. In meshed engagement with the gear 6| is another gear 64 which is freely rotatable upon the contact drum shaft 65 but has integral therewith a synchronizing cam member 65 which if in synchronized relation with cam member 61 which is slidably splined to the shaft 65 will allow dropping of this cam member 61 to open contacts 68 and will also cause the contact drum shaft 65 to be rotated by the gears 5i and 64, As more clearly pointed out hereinafter if energy is applied to transfer an indication from a calculator contact mechanism to a particular indicating drum this drum will continue rotating, due to energization of its associated clutch, until (1) resynchronization of its associated cams 66 and 61 has taken place and thereafter 2) until the number drum 53 is in correspondence with the corresponding contact arm of the calculator. The clutch shaft 62 is driven by a motor M whereas the indicating shaft 65 is connected to its associated indicating contact drum Dl, D2, D3 or D4 and drives the same.

Each token hole TI-IA, etc. is provided with an east relay, such as, AERS or AER5 and with a west relay, such as AWR3 or AWR5 and each of the pairs, such relays as AER3-AWR3 has associated therewith a repeater relay ARR3 and a.

i6 clutch relay ACR3. The purpose of these relays will be more fully described hereinafter.

Operation of transfer mechanism.-Let us assume that the hour and minute wheels EHA an-d EMA respectively of the eastbound calculator indicate 2:20 oclock which is the starting time as indicated for the calculation set up in the tabulated analysis, third calculation of Fig. 5. Under the assumed condition the four Contact arms EHTA, EHUA, EMTA and EMUA will assume the positions as indicated in Fig. 4B. As heretofore explained a particular :altitude ight 9 over the ground route under consideration has been set up on the board asindicated by the three tokens 9T in Fig. 4A (four tokens in Fig. l) If now the dispatchery desires to transfer to, or rather duplicate the starting time on, his panel board he will depress token 9T for location A. This causes closure of contact 'IG associated with the token receptacle in which the starting token 9T is inserted. resulting in the picking up of token relay AER3. Had the token pointed to the left the contact l! would have closed, the relay AWRS would have picked up and the westbound instead of the eastbound calculator would have been electrically connected to the transfer mechanism. Upon release of the token the contact 'ill will again open. The closure of front contacts 'i2 and I3 apply respectively positive and negative terminals of a source of current to the two terminals of the clutch -coil 63 of each of the digit drums 53 through two circuit controlling drums one associated with the east calculator (unit A) and the other with the indicating shafts 65.

This contact 'f2 also energizes the aligning magnet 82E (see Fig. 3) which upon being energized causes the V-knife S3 to engage one of the sixty slots between the sixty teeth on wheel 5| to cause the contact arms EMTA and EMUA (see similar arms EMTA and EMUA in Fig. 3) to take positions so that these contacts engage at least one and not more than one stationary contact. Also in order to reduce friction within the calculator the movable contact arms preferably are out of contacting relationship with the stationary contacts except when this magnet 82E is energized.

The front Contact I4 of relay AER3 also closes and applies positive potential from the same source to each of the contacts 6B associated with the correspondence cams (5B-B1 `so that if any one of these indicating numbered drum-s 53 is out of synchronism with its associated indicating shaft S5 the associated clutch coil will -be energized through a second circuit. This second circuit for the clutch coil will of course open when synchronization between the indicating drum 53 and the conta-ct drum D has been consummated. The closure of Contact l5 of relay AER3 picks up the repeater relay ARRS which would, by the closure of its front contact '16, apply energizing current to the four lamps 5S, 57, 58 and 59 were it not for the fact the energizing circuits for these lamps are open at back contact 'Il of relay AERB.

It will be observed that the clutch relay ACR3 has four windings which are respectively connected to the four input terminals of the four clutch coils 63. This clutch repeating relay ACRB is employed to manifest by its dropping that all of the four numbered drums 53 foi` that indicator have completed their operation. This relay ACES is of course picked up in response to picking up of either of the relays AER3 or AWR3 unless all of the numbered drums 53 were already intcorrespondence-:with the-indication". displayed. onxthecalculator forthatsstation: The moment 1 anyi-one tof the?clutch-imagnets63.for1this, indie.4

catorais. energized. ineresponse `to the-picking up of relayxAER3 the. relay-'ACES -pickszup` and atv` its front contact 13 closes a stick circuitl for this tolr'en-y relayjAER includ-ingA the.-sticlc-. Contact 1E! of thistoken relay AERE.

Let usnow-assume; that the indicating drums up Awhich then sticksfupl-through a stickzcircuit incluld'ingl"itsv stick-'.contact 80; and thee stem of Since.the firstfand the theassociatedl-token 9T;` fourth indicatingfdrum; namely,Y thetens. hour, drum :53 andthe-units mnute'drum 53 `respecttively already assumer. the-esame position as as-v1 sumed .by the rcorresponding;,Contact arms EHTA and .EMUAI namely,y the izeroipositon; no circuitsv for the clutch cc-'ils- Blf'fer :these drums 53 will be completed Aecircuit for thefunitsrhour indicatingV drumk clutchmagneti 3-:is lhowever .completed which may be-.tracedfrom the :positiveterminal of a local source, through frontcontara-t1?.i ofthe.L

rel'ay-AERSWthroughrcontact Karm` EHUA; wire12,

conductingfdrumiD2;v Wirefi I, clutch-magnet coil yt3 ff or the unit hour' indicating {drum- .-53 .through i ront contact 13 tof, .relay AER3-to the-negative v terminal. of thesamersource..

In .theievent the numbered indicating-'drum 53 e;

is .not VVin synchronism: with .itsf associated: indicatingf vshaft Svanothercircuitfor this# same Clutch magnet 63is:closed through front contactv 14 I`of. l relay iAER3 and. synchronizingaj;contacta-68e.. With .the Yclutch magnet 63A for; the-second digit noffrenergized the associated numberldrum53L-is Y mechanically` connected to the` associated motor M Vand :will continue to rotated tuntilfsynchro- I nizationbetWe-en .this drum 53 of the second digit;

and .the shaft 65fhassbeenconcluded... Thisre sults intheopeningvof.Contact 68=and incontinued. rotation .ofy this drum 53.untilfcontact drum/ DZ-has rotatedto apoint `where wire 2 and'its contact ride on the gap or onsaniinsulated-portionvof this :drums D2.v(as.shown .in-Fig. 4B). The

numbereddrum.. 53 will. thenndisplay `the number H2."the sameas .assumed tobe displayed in'the.

rightehand column. onthel hour .Wheel EHA.l the .samev manner ,as just `pointedr outl the 4third numbered-"drum 53 is also operatedy to the posi. tion to display andnumber .2.

Alllorthe four coilsof thefclutch repeating relay'ACRLSai-e now deenergized `thereby openingl front contact 181er this relay and causing deenergizaition of token. relay AERIL The 4drop-- ping of this relay AER`3 .fatits ybackcontact-TT closes an energizing circuitforeach of .the llampsr 56',` 51;"l 58"`and 59'v resulting in the displayfof the starting;timeA 220"for flight Baatstation A.f. It

willfbe noted that .the European.V hour.system1is Y.

employed so as .to removefthe need forA. M. and P. M. designation.

Let 'us now assumethlat the planefhasfstar-ted out andthat there is no longenany needV of: either providing protectionagainst thisplaney or indicate its startinggtime..

The .dispatcher y maynow withdraw the tokenTat theV station A-.location.

which will result in fthe droppingp repeater 1s:` relay ARR3 vand theiextinguishment of lamps 56,v 51, 58 and 59 for theindicator under consideration. The numerals on the fourdrums of this indicator are` now no longery Visible. It

yshould be understood that the tokens need only be -momentarily depressed to. display the time indication on the-panel board andthat in practice all the tokens yof-a particular Eight are preferably depressed-in rapid succession: The apparatus is `so constructed- .and the speed of the motors-are so .chosen'that a calculation ona calculator can be transferred fromsuchicalculator to the panel board'infabout one second.

Inpracticing the` invention-'it is proposed that about twenty-four number drums vbe supported directly over each other and that each-'of the indicator faces :be about one inch square. It is thus seen thatl the mechanism for operating these drums- 53-must besupported directly back of the sdrum and shouldnotloc larger than the vface of they indicator. As shown, each vertical rovvv of indicating drums sfprovidedwith a' single driving shaft 62.andra.sngle'indicatingshaft 65.` The -driving shaft 62\ is operatively connected to .oneor more vdrums 53 by one or more energized clutches. and*y the synchronizing cams are so shaped that the gear can drive the indicating shaft lbut the-'indicatingzshaft 65 lcannot driver the gear 64.- If more than one clutch magnet 63 is energized at a time and the contact drum, such as. drum DI is out of synchronism with its associated indicating shaft some: time may elapse before these-two elements vgetinto synchronism because underl thiscondition one'of the fsynchrolnizing. cams` 66 may be driven by its gear 64 Whilethe-other synchronizing-cam 61 is driven by the indicating shaft 65 .due to the indicating shaft being. drivenby-some other indicator. Since both ofV these. elements .are probably rotated at the same speedand in the same direction no resynchronization ofthe two cams can take place until the-indication shaft is no longer driven due to someother clutch magnet in the same -vertical row beingenergized.: After this resynchronization of the itwocams 66 and 61 takes place the clutch magnetremainsenergized only untilthe indicating'drum 53 under consideration gets in synchronism with the calculator contact arm'.

Oneiofhthevdiiicult problemsssolved -by the present invention,;especial1y the invention as disclosed in. the-modiedconstruction .(Fig; '1) is due ,tothe smalll amount of space'available for the `display of eachf; digit-v of theY starting and arrival time indicatorson the panelfboard; The displayframe foreach. digit numberv should not be larger than loneinch square.` This problem has been. solvedJin.the moclied form ofthe invention` showniinFigs. '1, 8, 9and vlO-by the provision of'fa .compact contactdrum lless -than onev inchin diameteriforeach digit. the synchronizing shafts 651 and.. associatedy synchronizing cams shown in Fig, .4.of the. drawings are no llonger necessary., and( have been dispensed with. viewof theintricate mechanismnecessary-to display these starting and Yarrival. ltimeI `indications andfrepars may at times becomenecessary it is essential that certainof the indicatingapparatus bel'construe'd to' be detachably associatedwth the drive vshaft. The 'rnodied apparatus of Fig. 7 is so constructedth'at'the indicator may be removed fromthe'frontfofrthe panel and so that the contact drum which is detachablyassociated with th'e l=-illmninated"fin'dicator by interm'eshed gears may'irbewvithdrawn from the `rear 7Aof` the panel.Y

Modified:constructions- InlFigs: '1,lr 8,v 9 and 10H has been illustrated a modified form of illuminated indicator unit comprising a portion of a vertical shaft 90 which is more or less permanently pivoted in bearing plates 9|. These plates 9| (see Figs. '1 and l0), only one being shown. are fastened to vertical struts 92 to which are welded, or otherwise secured, angle bars 93 arranged in pairs to constitute slides into which the indicating unit I and the contact unit J are adapted to slide. It should be noted that these units I and J are not in alignment (see Fig. 10). This non-alignment is due to the fact that the shaft 95 of the indicating unit I must be in alignment with the shaft 90 whereas the shaft 96 of the contact unit J must be out of alignment with this shaft 90 (see Fig. 10).

Referring to Fig. 7 the indicating unit I includes cup 91 of magnetic material in which is contained the clutch coil 98 to constitute an ironclad clutch magnet having associated therewith a circular armature 99 flXedly pinned or keyed to the shaft 95. The armature 99 is held in its retracted position by a coil spring contained on` and surrounding the shaft 95 and located between the armature 99 and the non-magnetic plate |0|. A bearing bracket |02 pivotally supports one end of the shaft 95 whereas the other end is supported by a bearing hole in bottom of the cup 91. One end of the shaft 95 is pinned into a double gear |03-|04 constituting a bevel pinion |93 and a spur pinion |04. In order to bring this gear and in turn the indicating belt to a sudden stop a braking surface |20 has been provided and so located as to be engaged by the gear |04 when the clutch 98 is deenergized. The other end ofthe shaft 95 is splined into the bevel pinion |05 to constitute a slidable driving connection, that is, the shaft 95 may be moved endwi-se against the force of the spring |00 but for all position is in driving relation with the pinion 05. In fact energization of the clutch coil 98 will cause the armature 99 to be attracted to the cup-shaped core, the shaft 95 also being magnetizable, to cause the bevel pinion |03 to mesh with bevel pinion |06 pinned to vertical shaft 90, as a result of which this pinion |06 will rotate bevel pinion |05. The` pinion |05 is also pivotally supported in bracket |02.

To the bottom plate of the indicating unit I is secured a pin |01 on which is pivoted the double pinion IBS-|09 constituting a bevel pinion |08 and a spur gear |09. The bevel pinion |08 meshes with bevel pinion |05 whereas the spur gear |09 meshes with a spur gear ||0 connected to the bottom end of the drive pulley pivoted on a pin ||2. Near the front of the indicator unit I are two vertically disposed pins 3 (see Fig. 8) on each of which is pivotally supported a preferably transparent roller ||4. A translucent belt ||5 having numerals painted, or otherwise placed, on the inside thereof so as to be visible only if the compartment inside this belt is illuminated, as by the lamp H6, surrounds the drive pulley and the idler pulleys ||4. This belt ||5 is preferably perforated to receive short pins- ||1 so as to assure that this belt ||5 maintains a predetermined relation with spur pinion |94 `and the spur pinion ||8 on the shaft 96 meshed therewith. The front end of the indicating unit I is provided with a cover glass ||9 held in Vplace by a bezel |20.

The base for the contact unit J constitutes a U-shaped channel |25 (see Fig. 9) having an upbent end |25a (seeFig'. 7) against which is fastened a circular insulating plate |29 about which is secured a conducting ring |26. The long sleeve 94 constitutes a bearing for the shaft 96. This conducting ring |26 constitutes a support for the Xed ends of ten contact lingers 0 to 9 inclusive (see Figs. 9 and 11).

In the opposite end of the channel with respect to the conducting ring |26 is secured, as by screws |213, a circular insulating plate |21 having two circular rows of eyelets |28 which support front and back contacts also numbered 0 to 9 inclusive cooperatively as-sociated with the contact fingers 0-9 supported by ring |26. Each row of these eyelets |28 is connected to wires 0 to 9, inclusive (see Figs. 7 and 11), by a detachable plug coupler constituting a circular insulating plate |2|, provided with pins |22 connected to these wires, as by screws |23. A center pin |22 is also provided to connect wire |33 (see Figs; 7 and 1l) to ring |26 through the medium of the jumper |32. The spring fingers 0 to 9 normally, eX- cept for one, engage the inner row or back contacts 0-9 inclusive, which one contact is held in engagement with the front contact (contact 0 as shown) by the cam roller pivotally supported in the cam |3| secured to shaft 96 as by the pin shown. The wire |33, as shown in Fig. 11, is in turn at times connected to the positive terminal of a source of current through the medium of front contacts |51 or |58 of relays AER4 and AWR4, respectively.

From the foregoing it is readily seen that if current is applied to the circuit including the clutch magnet coil 98, Wire |33 and one of the back contacts normally engaged by the spring fingers supported by conducting ring |26 that the clutch magnet coil 98 will attract its armature 99 to cause bevel pinion |03 to engage r0- tating bevel pinion |06 as a result of which the belt 5 and the cam 3| will be rotated until the roller |30 operates the spring contact finger through which this current is supplied from the conducting ring |26. That is, the clutch magnet 98 in response to lifting of the contact finger and deenergization of clutch magnet 98 causes the pinions |03 and |05 to be disengaged. The meshed relationship of the various gears and their gear Vratios is such that the roller will engage a contact assigned a particular number when that number on the belt |5 appears in the opening of the bezel |20.

Structure of moorden-At the top in Fig. 11 has been illustrated a recorder for recording the starting or arrival time indication displayed on the panel board on a record sheet. In this connection it may be stated that a recorder is very useful or even necessary to avoid the dispatcher placing the blame on the apparatus in the event of an airplane accident due to instructions issued by the dispatcher. Each of the recorders R1, R2, R3 and R4 is identical to the indicating contactor unit I-J shown in Fig. 7 aside from three exceptions (1) that the gear ||0 directly drives a type wheel one revolution for each revolution of the Contact cam |3|; (2) that suitable type inking or carbon ribbon for printing is provided; and (3) that the outside contacts or front contacts of the contactor J are omitted.

Referring again to Fig. 11 the four recordery mechanisms R1, R2, R3 and R4 are arranged sideby-side in fixed relation with a stationary magnet |4| and have arranged in alignment therewith a time stamp TS, preferably including a synchronous motor driven by alternating current from a source AC, so as to at all times correctly maniamasser# fest the time of l day =by--1suitable2ftime'=indicatingi type fwheels 'oni the-lowerifa'ce-l thereoff Directly" below* the type 'Wh'eelsiY |40 fand' belowlftheetime stamp TS is provided 1a roller |42 preferablylconstructed of 'hard rubber# andffixedlylfsupported on afshaft |42- pivotally'- supportediin a frame |43 -xedlyl supported 'oni Aa shaftll441`pivotedin bearings I 45 theconstr-uctim` being-such-*that tilting ofy th'eframe |43 about-theraxisl=offltheshaft |44 will cause the rolle`r`2|42lto move axially up or'down. One-'end v off-the#frame-|43llhasintegral therewith an armature |43 in 'i magnetic relationwith the corefof-th magnet I4|.l Oir the The roller |42 fisfprovidedfwithf:pins |42b en gagingholes -|5I inea xrecordsheet I5I, which sheet* is-l unwoundfrom a record roll- -fI 52A when` the. roller |42 isl rotated iny Ya counterhclockwise directonlas viewed1in-r1'"g.11. Fomfthis construction it is readily seenthatf the lenergization oi magnet I4Iwill attractthe armature-|43at to lift the roller |42 andin turn the record sheet I5| againstthe type wheels I4`Bfand-the time stamp TS ltoscausefthel timel offdayas'lmanifested` by the time stamp -TS l'and 3the-#tune'manifested Aby the type wheels I4||to lbe printed on the record sheet I5I. the dog |48 to fall into the -next slot-between teeth on the ratchet Wheel |412'E Upon deenergizationof the magnet |4| `tlie-'rollerfal'ls"backfto its-normal position and in so doing will rotate the ratchet Wheel |41 one tooth-and in turn rotate the roller I 42 to its next position'ito*advance-the record sheet to itsnextprinting-position. It is thus seen that'energization-offthe-magnet I4`I prints a record and deenergization of this` magnet advances the record sheet. A recorder such as shown at the top of Fig. llf'of the drawings is provided for` each four-'digit-'indicator on the board.

'Circuit structure 'Fg 11 .In` Fig. ll hasfbeen illustrated onev particularcircuit `structure wherehy the time indication-displayedpn the calculator shown in Figs. 2 and 3 'maybetransfelred or duplicated on a our--digitindicator; such as:

shown in Fig. 7, arrangedon'apanel' boardsuch as shown in l employing atoken control such as shown in Fig.v iAgandlioW` this indicationmay be recorded on av recorder R Fig. 4B`sh`ows how like iixed contacts associated with rotating .arms EMUA and WMUA'or corresponding. digits on the eastbound and' westbound calculators, respectively; are connected together. In Fig. 1l the ste ionary contacts |i-9 of the unit minutes digit UA and Wit/.QUA are similarly connected toge ner at the junction' |66' ofcables I3|4 and y|37 at which point these contacts are also connected to corresponding back contacts `of the. contact nected to front contacts D'to 9 respectively of the contacter J yof the unit minute indicatorI-J yfor altitude 40001 station A through .themedium of a able i2 slightly from the wiring-shownin Figs., 4A and'4B because no synchronizing',camfis employed 4inthe Fig. l1 structure andthe-'recording:mechanismR This -liftingof the ro11er|42 will causeV The Wiring shown infFig. ll cliiilersl 22".- and circuits therefore-have been added to Fig. li.

The token IllTl andthe` relays AWR4,' AERA and kACRAI controlled'thereby are the same and are controlled in. like manner as similarly designated` devices `shown-in Fig...4A and for this on like contacts have been designatedv by like er reference'characters. An additional and slow acting printing relay APR4 Vhas however been employed. This 1elay`APR4 is controlled by a circuit including back contacts |54 and |55 of relays A'WRA and AERA respectively and front contact |56 'of the repeater relay ARR4fin series. The clutch coil' il' of the recorder R4 is rendered active through front contacts |6I and |52 of relays AREA and 'APR4f.respectively, Whereas the mting magnet I4| ofthe recorder is controlled .rough back contact |63 of relay ABBA and iront contact |64 rof slow droppingrelay APR4, respectively, in series: Energy is applied to the contact ring |23 of contactor J v(see Figs. 7 and il) through iront contactsy |51` or |58 or" relays AER or AWR4,--respectively, Whereas the contacts |59 and |661' of these two relays select the proper energizing the-.contact arm- ElVlTUA` or il/"JMUA'r as conditions require. Similar circuits are provided ior the apparatus ol the tens and units hour and the tens minute indicatorandrecorder units, and this apparatus vis duplicated for 'each' fourvdigit indicatorland recorder.

Operation Fig. 11.-Referringfto`ligsZA'or a moment. let us assume-thatftheininute'drurn EMA.

dica-tors I such as shownin 'Figs.-7-'l0 vand conventionally showninFig.' 11;' VVemustfoi course assume that a ilight; which-wef will forconeA venience call flight l);` has been Set up over a ground routeandthat ythiseili'ghtfisto start at altitudevfiOlO-'andy at station A and is indicated by flight tokens `'HIT of which only one has been illustrated in Fig.' l1.

Let us refer to Fig. 11- land assume that the dis- ,y patcher in'his desire to duplicatertheZl minute reading on the eastbound calculator on his digit indicator IJ (see Fig. '7) and that in order to do so he clepresses the token IT. Depression of the token IDT will result inthe completion of a circuit for the token relay AER4 through the back contact 'l0 'of the token receptacle, resulting in the energization of'this relay AER4. The piel;- ingup of thel relay AER4 -results in the picking up of the repeater relay ARR4 through front contact I5 ofthe toiien relay AER4. The picking up of the token relay AER4also results in the closure of front contacts |5'I'fand |59of'thi's relay resulting in'theconipletion ol. anenergizing circuit for the `clutch magnetQBfWhich circuit may' GO be traced from vthe positive terminal of a suitable source or" current through .iront contact. i5? of.

this relay AER4; through Wire |33.'` to contact ring LIZE, through'the"particular back contact of the. Contact mechanism J connected to the stationary contact with which the rotating arm EMUA of theeastbound calculator is in engagenient, namely, contact I, through front Contact of the relay AER'4, through a multiple path including the clutch `coil 98"and 'one `ofthe coils of the relay ACR4, connected in multiple; to the other or 'negative terminal of "saiclsource rlhe closure of this circuit will result in the" picking up of the clutch repeating relay ACR4/which hy` the closure of its fron-t contact' 18 'will lcomplete a stick circuit -for1tlieftoken're1a`y AERl'.`

eastbound or Westbound calculator byv is move-:l to the Qlkninuteposi-tionl and thatr it is desired to transmitl this-indication toin-A 

